Dual-mediated polymerizable composite for additive manufacturing

ABSTRACT

A formulation for a photopolymer composite material for a 3D printing system includes an acrylate monomer or an acrylate oligomer, an inorganic hydrate, a reinforcing filler, a co-initiator, a thermal initiator, and an ultraviolet (UV) initiator. In the formulation the acrylate monomer or the acrylate oligomer may be between about 10.0-30.0 w % of the formulation. The thermal initiator may be between about 0.001-0.05 w %, the co-initiator may be between about 0.001-0.05 w %, and the UV initiator may be between about 0.001-0.2 w % of the formulation. A method of generating a formulation of a photopolymer composite material for use in a 3D printing system includes using an acrylate monomer or an acrylate oligomer, an inorganic hydrate, a reinforcing filler, a co-initiator, a thermal initiator, and an ultraviolet (UV) initiator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/541,027, filed Aug. 14, 2019, which is a continuation-in-part of U.S.patent application Ser. No. 16/276,521, filed Feb. 14, 2019, whichclaims the benefit of U.S. provisional patent application Ser. No.62/630,725, filed on Feb. 14, 2018, wherein the contents of all thepreceding applications are incorporated herein by reference in theirentirety.

BACKGROUND

Three-dimensional (3D) printing, also known as additive manufacturing,is a technique that deposits materials only where needed, thus resultingin significantly less material wastage than traditional manufacturingtechniques, which typically form parts by reducing or removing materialfrom a bulk material. While the 3D printed articles were generallymodels, the industry is quickly advancing by creating 3D printedarticles that may be functional parts in more complex systems, such ashinges, tools, structural elements.

In existing 3D printing processes, a 3D object is created by forminglayers of material under computer control without molding. For example,3D information of a structure is determined using computer 3D modelingfragmentation and a prepared mixture can be fed from a nozzle bymechanical control to print the structure.

One serious problem and challenge of 3D printing is that printingmaterials meeting requirements of certain applications can be veryscarce. For example, existing printing materials are mainly organicmaterials. The organic materials are printed in a molten state at a hightemperature via layer by layer deposition. Curing of the organicmaterials is prone to oxidation decomposition, and the preparation andprinting processes may emit unpleasant toxic gases that harm theenvironment and human health. In addition, the organic materials may beprinted under demanding conditions which incur high costs. Structuresprinted with the organic materials may have poor mechanical propertiesand are therefore not suitable for certain applications such asconstructing livable buildings, thus limiting the application of 3Dprinting technology to a certain extent.

Another example of printing material is cement-based materials such asconcrete. Cement-based materials generally take a long time to solidify.Thus, such materials generally cannot meet performance requirementsrequiring the material to rapidly solidify in a short period of time.Even though the speed of solidification can be increased by changing theformulation, such increase is usually limited or difficult to controland makes 3D printing impractical for certain circumstances such asconstructing a building on a construction site.

In view of the foregoing, there is a need for improvements and/oralternative or additional solutions to improve 3D printing materials andprocesses.

In conventional additive or three-dimensional fabrication techniques,construction of a three-dimensional object is performed in a stepwise orlayer-by-layer manner. In particular, layer formation is performedthrough solidification of photo curable resin under the action ofvisible or UV light irradiation. Two techniques are known: one in whichnew layers are formed at the top surface of the growing object; theother in which new layers are formed at the bottom surface of thegrowing object. Photochemical curing, also known as photopolymerization,is an inexpensive and efficient method of additive manufacturing.

The main drawback of light-curing is the limited penetration of lightradiation into the irradiated material, which gets even more limited inpresence of colored, semi-transparent, or opaque additives, which arefrequently used to give the material functional properties. In any knownlayer-by-layer printing process using polymer materials, the polymermatrix embedded with the composition of the filler must allow UV lightpenetration depth to be sufficient for a complete layer solidification.

The other issue related to photopolymerization is that non-uniformvolume shrinkage may occur upon polymerization, which results in a highlevel of residual stress and detrimental warpage or curvature of theprinted samples. The bulk volume shrinkage in photopolymerization is anunavoidable result of the formation of new covalent bonds via the vander Waals force. As a result, polymerization strains are introducedincrementally, layer-by-layer during 3D printing, thereby giving rise toresidual stresses. If the stress exceeds the adhesive strength of anycomponent of the system, micro- or macro-deformations occur (cracking,delamination, etc.) during and after printing.

Retailleau, Ibrahim and Allonas, Polymer Chemistry 5, 6503 (2014),describe UV-curing polymerization of acrylates assisted by a thermalpolymerization, but their proposed system requires a significant time tocure at the surface. Thus it does not fit for additive manufacturing,especially for extrusion-based additive manufacturing, and no suggestionis made on how those materials may be adapted to additive manufacturing.

Rolland, and Menio, patent application WO2017040883A1, describe a dualcure cyanate ester resin for additive manufacturing. McCall, patentapplication WO2017112521A1, describes dual curepolyurethane/polyurea-containing resins for additive manufacturing. Bothabove-mentioned applications describe combinations of layer-by-layerphotopolymerization, preferably DLP or CLIP methods, followed by thermalcuring to form two interpenetrating polymer networks. A shortcoming ofthis method is the need to perform additive manufacturing in twosubsequent stages, which increases production time and required labor,and adds additional equipment costs.

Therefore, there is a need to develop a novel composite that will solvethe above-mentioned shortcomings of the existing formulations.

BRIEF SUMMARY

This disclosure relates to a formulation for a photopolymer compositematerial for a 3D printing system comprising at least one of an acrylatemonomer and an acrylate oligomer in the range between about 10.0-30.0 w% of the formulation. The formulation further comprises an inorganichydrate in the range between about 5.0-30.0 w % of the formulation. Theformulation further comprises a reinforcing filler in the range betweenabout 50.0-80.0 w % of the formulation. The formulation furthercomprises an ultraviolet (UV) initiator in the range between about0.001-0.2 w % of the formulation. The formulation further comprises athermal initiator in the range between about 0.001-0.05 w % of theformulation. Finally, the formulation comprises a co-initiator in therange between about 0.001-0.05 w % of the formulation.

This disclosure also relates to a method of generating a formulation ofa photopolymer composite material for use in a 3D printing system. Themethod comprises adding at least one of an acrylate monomer and anacrylate oligomer in the range between about 10.0-30.0 w % of theformulation, an ultraviolet (UV) initiator in the range between about0.001-0.2 w % of the formulation, a co-initiator in the range betweenabout 0.001-0.05 w % of the formulation, an inorganic hydrate in therange between about 5.0-30.0 w % of the formulation, and a reinforcingfiller, in the range between about 50.0-80.0 w % of the formulation, ina blender. The method further comprises generating a resin premix byblending the acrylate oligomer, the UV initiator, inorganic hydrate,co-initiator, and the reinforcing filler through operation of theblender for a first amount of time. The method further comprisescombining the resin premix with a thermal initiator in the range betweenabout 0.001-0.05 w % of the formulation in the blender. Finally, themethod comprises generating a photopolymer composite resin by blendingthe thermal initiator and the resin premix through operation of theblender for a second amount of time.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

To easily identify the discussion of any particular element or act, themost significant digit or digits in a reference number refer to thefigure number in which that element is first introduced.

FIG. 1 illustrates an end material 100 in accordance with oneembodiment.

FIG. 2 illustrates an end material 200 in accordance with oneembodiment.

FIG. 3 illustrates a system 300 in accordance with one embodiment.

FIG. 4 illustrates a system 400 in accordance with one embodiment.

FIG. 5 illustrates a method 500 in accordance with one embodiment.

FIG. 6 illustrates a system 600 in accordance with one embodiment.

FIG. 7 illustrates a method 700 in accordance with one embodiment.

FIG. 8 illustrates cellular structure concepts 800 in accordance withone embodiment.

DETAILED DESCRIPTION

A photopolymer composite material construction material combinesproperties of a polymer matrix and microcrystalline inorganic fillers,which have a monolithic amorphous structure with low porosity. Thematerial comprises a base photopolymer, ensuring layers chemicallyadhere to each other during the printing process. With thelayer-by-layer deposition of the material in the 3D printing process,each new curable layer is firmly fixed to the previous one due to thechemical adhesion between liquid and cured polymer matrix. Duringexperimentation, the photopolymer composite material forms a solidmonolithic structure with layer-by-layer curing. Polymer and inorganicpails of the compound act synergistically, the polymer matrix provideshigh compressive strength, as well as coats the filler particles,protecting them against aggressive environmental exposures (moisture,acids, alkali, etc.). Further, the presence of the inorganic componentsdecreases the plasticity of the photopolymer composite, resulting inhigher tensile strength.

TABLE 1 Components of Photopolymer Composite for 3D Printing ComponentsQuantity Ranges Acrylate Oligomer 20.0 to 60.0 w % Inorganic Hydrate20.0 to 70.0 w % Reinforcing Filler  5.0 to 60.0 w % UV Initiator 0.001to 0.2 w % Dye/pigment 0.001 to 0.05 w % 

Referencing Table 1, a formulation for a photopolymer composite materialfor a 3D printing system may include an acrylate oligomer, an inorganichydrate, a reinforcing filler, and an ultraviolet (UV) initiator. In anembodiment of the formulation the acrylate oligomer may be found rangingbetween about 20.0-60.0 w % of the formulation. The inorganic hydratemay be found ranging between about 20.0-70.0 w % of the formulation. Thereinforcing filler may be found ranging between 5.0-60.0 w % of theformulation. And the UV initiator may be found ranging between about0.001-0.5 w % of the formulation.

In some configurations, the acrylate oligomer may be Triethylene glycoldimethylacrylate (TEGDMA). Some properties of TEGDMA are found in Table2.

TABLE 2 Triethylene Glycol Dimethacrylate (TEGDMA) Parameter ValueChemical formula CH₂═C(CH₃)COO(CH₂CH₂O)₃COC(CH₃)═CH₂ Density 1.092 g/mLRefractive index 1.46-1.508 State of Matter Liquid Color Transparent

TEGDMA is a hydrophilic, low viscosity, difunctional methacrylic monomeremployed as a crosslinking agent. TEGDMA is a transparent liquid thatmay found ranging between about 20 to 60 w % of the formulation.

In some configurations, the organic matrix may be TrimethylolpropaneTrimethacrylate (TMPTMA). Some properties of TMPTMA are found in Table3.

TABLE 3 Trimethylolpropane Trimethacrylate (TMPTMA) Parameter ValueChemical formula [H₂C═C(CH₃)CO₂CH₂]₃CC₂H₅ Density 1.06 g/mL Refractiveindex 1.472 State of Matter Liquid Color Yellow

TMPTMA is a hydrophilic, low viscosity, reactive trifunctionalmethacrylate suitable for use in a wide-ranging number of polymer crosslinking functions. TMPTMA is a transparent liquid that may found rangingbetween about 10 to 30 w % of the formulation.

In some configurations, the organic matrix may be Poly(ethylene glycol)dimethacrylate (PEGDMA). Some properties of PEGDMA are found in Table 4.

TABLE 4 Poly(ethylene glycol) dimethacrylate (PEGDMA) Parameter ValueChemical formula C₃H₃C(O)(OCH₂CH₂)_(n)OC(O)C₃H₃ Density 1.099 g/mLRefractive index 1.464-1.468 State of Matter Liquid Color Transparent

PEGDMA is a long-chain hydrophilic, crosslinking monomer. PEGDMA is atransparent liquid that may found ranging between about 10 to 30 w % ofthe formulation.

In some configurations, the inorganic hydrate may be borax decahydrate.Some properties of borax decahydrate may be found in Table 5.

TABLE 5 Borax Decahydrate Parameter Value Chemical formula Na₂B₄O₇•10H₂OState of Matter Solid Powder Volume weight 0.85 g/cm³ Initialdecomposition temperature 60-70° C. Refractive index 1.46-1.47 Foreignimpurities No impurities Particle size distribution D (10)  110 ± 20 μmD (50)  310 ± 40 μm D (90) 700 ± 120 μm D max 2800 ± 300 μm  Solubilityin organic matrix Insoluble

The inorganic hydrate may be a borax decahydrate such as sodium boratedecahydrate. Borax decahydrate is a solid white powder that may beprovided in large bags for industrial use. Borax decahydrate may befound ranging between about 22.0 to 25.0 w % of the formulation whencombined with aluminum oxide trihydrate but is not limited thereto. Insome embodiments, the borax decahydrate may be found ranging between20.0 to 45.0 w % of the formulation.

In some configurations, the reinforcing filler comprises at leastaluminum oxide trihydrate or an aluminum oxide trihydrate mixture withat least one of calcium carbonate, talc, silica, wollastonite, calciumsulfate fibers, mica, glass beads, glass fibers, or a combinationthereof. Some properties of the aluminum oxide trihydrate that may beshared with the aluminum oxide trihydrate mixture may be found in Table6.

TABLE 6 Aluminum Oxide Trihydrate Parameter Value Chemical formulaAl(OH)₃ State of Matter Solid Powder Volume weight 0.7 g/cm³ Refractiveindex 1.56-1.58 Foreign impurities No impurities Particle sizedistribution D (10)  5 ± 1 μm D (50) 25 ± 5 μm D (90) 85 ± 15 μm  D max200 ± 50 μm   Solubility in organic matrix Insoluble

Aluminum oxide trihydrate, (aluminum hydroxide, (Al(OH)₃)) is providedas a solid white powder that is insoluble in the acrylate oligomer. Thealuminum oxide trihydrate may be found ranging between about 52.0 to55.0 w % of the formulation.

In some configurations, the UV initiator may be bisacylphosphine oxides(BAPO)s. Some properties of the BAPO may be found in Table 7.

TABLE 7 Bisacylphosphine oxides (BAPO) Parameter Value Chemical formulaPhenylbis(2,4,6-trimethylbenzoyl/phosphine oxide State of Matter SolidPowder Color Yellowish Solubility in High solubility organic matrix

The UV initiator is the component which starts the polymerization underUV-light of a specified wavelength.

In some configurations, a dye may be found ranging between about 0.01 to0.05 w % of the formulation. Properties of photopolymer composite resinare dependent on the quantity of the components utilized in theformulation. When uncured, the material is thixotropic liquid. Thematerial may be transported through the feeding route by pumps, thenextruded, and then it solidifies under UV-light. When being exposed toUV-light, the substance, which is called an initiator, starts thepolymerization reaction, which is exothermic. Table 8 illustrates someproperties of the photopolymer composite resin.

TABLE 8 Properties of Liquid Polymer Resin of the Photopolymer CompositeParameter Value Density 1.35 to 2.00 g/cm³ Maximum cure depth 5-15 mmunder visible UV light Maximum temperature 60-65° C. duringpolymerization

In some configurations, the upper limit of the density of the liquidpolymer resin may be higher, as the density of liquid polymer resin maybe due to limitations of the feeding system. In some instances, theupper limit of the density may also be determined by the bulk weight ofthe fillers utilized in the formulation.

A method of generating a formulation of a photopolymer compositematerial for use in a 3D printing system may involve combining anacrylate oligomer, ranging between about 20.0 to 60.0 w % of theformulation, an ultraviolet (UV) initiator, ranging between about 0.001to 0.5 w % of the formulation, and a reinforcing filler, ranging between5.0 to 60.0 w % of the formulation, in a blender. In the method, a resinpremix may be generated by blending the acrylate oligomer, the UVinitiator, and the reinforcing filler through operation of the blenderfor a first amount of time ranging between about 5 and 20 minutes. Inthe method, the resin premix may be combined with an inorganic hydrateranging between about 20.0 to 70.0 w % of the formulation in theblender. In the method, a photopolymer composite resin may be generatedby blending the inorganic hydrate and the resin premix through operationof the blender for a second amount of time ranging between about 10 and14 hours.

In some instances, the photopolymer composite resin is loaded from theblender into a mixing tank of a 3D printing system. In some instances,the photopolymer composite resin may be loaded from the blender into asecond drum for storage. The photopolymer composite resin may then bemixed in the second drum with a mixer after a time interval rangingbetween 3 hours to 7 days. A mixed photopolymer composite resin may thenbe transferred from the second drum into the mixing tank of a 3Dprinting system. In some configurations, the photopolymer compositeresin is combined with a dye ranging between about 0.01-0.05 w % of theformulation in the second drum through operation of the mixer.

In some configurations, the acrylate oligomer may be Triethylene glycoldimethylacrylate (TEGDMA) and may be found ranging between about 23.0 to27.0 w % of the formulation. In some configurations, the inorganichydrate may be borax decahydrate and may be found ranging between about22.0 to 25.0 w % of the formulation. In some configurations, thereinforcing filler comprises at least aluminum oxide trihydrate or analuminum oxide trihydrate mixture with at least one of calciumcarbonate, talc, silica, wollastonite, calcium sulfate fibers, mica,glass beads, glass fibers, or a combination thereof. In someconfigurations, the aluminum oxide trihydrate may be found rangingbetween about 52.0 to 55.0 w % of the formulation. In someconfigurations, the UV initiator may be bisacylphosphine oxides (BAPO)s.

The present invention is related to a new composition that comprises apolymer matrix, inorganic fillers and a complex of polymerizationinitiating agents, providing a stable single-stage 3D printing process.In some embodiments, the invented composition may include a flexiblevariation of the printing speed and embed into the polymer matrix themineral fillers of different nature, including semi-transparent, opaque,and colored particles.

To resolve the existing issues, the dual cure process may be implementedby using the co-initiation system, including the use of photoinitiators, thermal initiators and others. The application of dualinitiation system may open opportunities for the on-demand curing ofpolymer materials. A composite material may combine properties of apolymer matrix and microcrystalline inorganic fillers. The material maycomprise a base acrylate monomer and/or acrylate oligomer, fillercomposition, and a system of co-initiating agents of photo- andthermal-polymerization, which may induce a dual-cure reaction of themonomer/oligomer ensure a stable printing process.

With the layer-by-layer deposition of the material in the 3D printingprocess, each newly deposited layer may undergo consistent photo- andthermal-polymerization curing. Properties of photopolymer compositeresin may depend on the quantity of the components utilized in theformulation. When uncured, the material may be a thixotropic liquid. Thematerial may be transported through the feeding route by pumps and thenextruded. When exposed to UV light, a photo-initiator or UV initiatormay begin the polymerization reaction, causing a cured shell to form onthe surface of the deposited layer, while the core remains uncured.Through the UV curing of the shell, each newly deposited layer mayfirmly adhere to the previous layer, preserving layer dimensions andform.

The combination of the thermal initiator with an appropriate promoter(co-initiator) may allow thermal polymerization to proceed at arelatively low temperature. Because photopolymerization is an exothermicprocess, it may induce the sequential process of thermal initiation,which may prolong the polymerization time (the polymerization stressrelaxation period). Prolonging the polymerization time may reduce oreliminate deformations and may make the volume shrinkage more uniformand controllable. As a result, a layer-by-layer structure may be formedwith high adhesion between the layers, reduced anisotropy, and,consequently, enhanced mechanical performance. Thus, this dual curetechnique may solve the most important issues occurring during3D-printing by photopolymerization.

TABLE 9 Components of Dual-Care Composite for 3D Printing ComponentsQuantity Ranges Organic Matrix  10.0 to 30.0 w % Inorganic Hydrate   5.0to 30.0 w % Reinforcing Filler  50.0 to 80.0 w % UV Initiator  0.001 to0.2 w % Thermal Initiator 0.001 to 0.05 w % Co-initiator 0.001 to 0.05 w% Dye/pigment 0.001 to 0.05 w %

Referencing Table 9, a formulation for a composite material to be usedin dual cure 3D printing may include an organic matrix comprising atleast one of an acrylate monomer and an acrylate oligomer. Theformulation may further comprise an inorganic hydrate, a reinforcingfiller, a UV initiator, and a combination of thermal initiator andco-initiator (activator). In an embodiment of the formulation, theorganic matrix may be found ranging between about 10.0 to 30.0 w % ofthe formulation. The inorganic hydrate may be found ranging betweenabout 5.0 to 30.0 w % of the formulation. The reinforcing filler may befound ranging between about 50.0 to 80.0 w % of the formulation. The UVinitiator may be found ranging between about 0.001 to 0.2 w % of theformulation. The thermal initiator in conjunction with the co-initiatorin various ratios may be found ranging between about 0.002 to 0.1 w % ofthe formulation (the summation of each component being found rangingbetween about 0.011 to 0.05 w %).

In some configurations, the organic matrix may be Triethylene glycoldimethacrylate (TEGDMA). Some properties of TEGDMA are found in Table 2above. TEGDMA is a hydrophilic, low viscosity, difunctional methacrylicmonomer employed as a crosslinking agent. TEGDMA is a transparent liquidthat may found ranging between about 10 to 30 w % of the formulation. Anexemplary matrix may include different polymeric materials. Alternativepolymeric materials may include TMPTMA, as described in Table 3, andPEGDMA, as described in Table 4. In one embodiment, the polymericmaterial may include one or more acrylic oligomers. In an exemplaryembodiment, the acrylate oligomer is a mixture of TrimethylolpropaneTrimethacrylate (TMPTMA) and Triethylene glycol dimethylacrylate(TEGDMA) and is found in the range between about 10.0-30.0 w % of theformulation. In another embodiment, an exemplary matrix material may bepre-polymerized in order to enhance the viscosity of the composite.

In some configurations, a combination of inorganic fillers comprising atleast one reinforcing filler and inorganic hydrate may be used. Theinorganic hydrate may be an inorganic mineral possessing the initialdehydration temperature range needed to keep the composite temperaturebelow the autocatalytic threshold during printing and a refractive indexconforming the refractive index of the cured organic matrix. In thedisclosed formulation, temperature control is achieved by a combinationof the matrix and the fillers. The inorganic additives (inorganichydrates) are characterized by a certain set of thermophysicalproperties (decomposition temperature, heat capacity, thermalconductivity), which maintain the maximum temperature of the materialbelow the autocatalytic threshold during printing.

In some configurations, the inorganic hydrate may be borax decahydrate.Some properties of borax decahydrate may be found in Table 5 above.Borax decahydrate is a solid white powder that may be provided in largebags for industrial use. Borax decahydrate may be found ranging betweenabout 5.0 to 30.0 w % of the formulation when combined with thereinforcing filler but is not limited thereto.

In some configurations, the reinforcing filler may comprise aluminumoxide trihydrate or an aluminum oxide trihydrate mixture with at leastone of calcium carbonate, talc, silica, wollastonite, calcium sulfatefibers, mica, glass beads, and glass fibers. Some properties of aluminumoxide trihydrate and aluminum oxide trihydrate mixtures may be found inTable 6 above. Aluminum oxide trihydrate is a solid white powder thatmay be provided in large bags for industrial use. Aluminum oxidetrihydrate may be used as a flame retardant and reinforcing filler forthe polymer matrix.

In some configurations, the UV initiator may be bisacylphosphine oxides(BAPOs). Some properties of BAPO may be found in Table 7 above. The UVinitiator may induce the polymerization of the organic matrix underUV-light of a specified wavelength.

In some configurations, the thermal initiator may be benzoyl peroxide(BPO). Some properties of BPO may be found in Table 10.

TABLE 10 Benzoyl Peroxide (BPO) Parameter Value Chemical formulaC₁₄H₁₀O₄ State of Matter Solid Powder Color White Solubility in TEGDMA15 w %, 23° C.

The thermal initiation may be launched by decomposition of the BPOcatalyzed by the amine activator.

The co-initiator may be Bisomer PTE. Some properties of co-initiator aregiven in Table 11.

TABLE 11 Bisomer PTE Parameter Value Chemical formulaN,N-BIS-(2-HYDROXYETHYL)- PARA-TOLUIDINE State of Matter Liquid ColorDark Orange Solubility in TEGDMA High Solubility

In some configurations, the co-initiator may be added into a formulationin advance or may be dissolved in a suitable organic solvent separatelyfrom the composition mixture and added into a formulation right beforeextrusion. The three-dimensional object is formed from the compositeresin premix containing components described above by additivemanufacturing process, typically layer-by-layer extrusion additivemanufacturing.

The formulation may be created following the method disclosed herein. Aresin premix may be generated by blending the acrylate monomers and/oracrylate oligomers, the UV initiator, the thermal initiator, the thermalco-initiator, and the fillers through operation of the blender for afirst amount of time. The photopolymer composite resin may then bycreated by blending the thermal initiator and the resin premix for asecond amount of time. Methods of generating the formulation aredescribed in further detail with regard to FIG. 6 and FIG. 7.

FIG. 1 shows an exemplary end material 100 that may be produced via 3Dprinting. The end material 100 is shown as including a matrix material102. The matrix material 102 may be formed via 3D printing.

Exemplary matrix material 102 may include a polymeric material. In oneembodiment, the polymeric material may include one or more acrylicpolymers. An exemplary acrylic polymer may include any polymer that is aproduct of polymerization of an acrylic acid, an acrylate (or ester ofan acrylic acid), and/or a derivative thereof.

The end material 100 may be formed by any suitable methods. An exemplarymethod may include polymerization. Exemplary polymerization may includephotopolymerization, such as radical photopolymerization. In oneembodiment, the end material 100 may be formed by a 3D printing processthat is based on photopolymerization. Exemplary 3D printing process mayinclude stereolithography (or SLA, SL, optical fabrication,photo-solidification, resin printing), binder jetting, directed energydeposition, material jetting, powder bed fusion, sheet lamination, vatphotopolymerization, or a combination thereof.

Referencing FIG. 2, the end material 200 is shown as including at leastone additive each being embedded and/or mixed within the matrix material202 at a selected concentration, respectively. Each additive may includeparticles and/or compounds that possess one or more selected properties.Advantageously, the properties of the additive may be imparted to theend material 200. As illustratively shown in FIG. 2, the additive in oneembodiment may include a first additive 204 and a second additive 206.Each of the first additive 204 and second additive 206 may provide arespective function to the end material 200.

In one embodiment, the additive may include a reinforcing additive. Thereinforcing additive may improve mechanical properties of the endmaterial 200. For example, the reinforcement additive may increasetensile, flexural, and compressive strength of the end material 200and/or decrease shrinkage of the end material 200 before and after 3Dprinting. Exemplary reinforcing additive may include calcium carbonate,talc, silica, wollastonite, clay, calcium sulfate fibers, mica, glassbeads, glass fibers, or a combination thereof. The reinforcing additivemay be mixed in the end material 200 in the form of particles. Thereinforcing additive particles may be in the form of round and freeformgranules, microcrystals of various shapes, fibers, threads, or acombination thereof. The reinforcing additive may be embedded in the endmaterial 200 at any suitable concentrations. For example, masspercentage (or weight percentage) of the reinforcing additive in the endmaterial 200 may range between about 5 to 70 w %, or from 30 to 50 w %of the end material 200.

Additionally and/or alternatively, the at least one additive may includea flame-retardant additive. In one embodiment, the flame-retardantadditive may be mineral-based and/or mineral-occurred. Stated somewhatdifferently, the flame-retardant additive may be of a natural origin.For example, the flame-retardant additive may be derived from a mineral.Exemplary flame-retardant additives may include aluminum oxidetrihydrate, sodium tetraborate decahydrate, boric acid, sodiumphosphate, ammonium sulfate, sodium tetraborate, aluminum hydroxide, ora combination thereof. In contrast to common halogen-based flameretardants, use of the mineral-based flame-retardant additive mayeliminate the presence of toxic substances in combustion products andadvantageously be environmentally beneficial.

Additionally and/or alternatively, the mineral-based flame-retardantadditive may be more resistant to blooming than non-mineral-based flameretardants, including phosphoric acid esters, aluminum polyphosphate,red phosphorus, and other halogen-free flame retardants. Advantageously,the functional stability of the end material 200 does not degrade withthe passage of time. The flame-retardant additive may be embedded in theend material 200 in the form of particles. The reinforcing additiveparticles may be in the form of round and freeform granules,microcrystals of various shapes, or a combination thereof. Theflame-retardant additive may be mixed in the end material 200 at anysuitable concentrations. For example, mass percentage of theflame-retardant additive in the end material 200 may range between about35 to 75 w %, or from about 45 to 65 w % of the end material 200.

Additionally and/or alternatively, the at least one additive may includea coloring agent for coloring the end material 200. Exemplary coloringagents may include a pigment, a dye, or a combination thereof.Additionally and/or alternatively, the at least one additive may includea glittering agent for providing a glittering effect to the appearanceof the end material 200. Additionally and/or alternatively, the at leastone additive may include an aromatic agent for generating an aromaticsmell from the end material 200. Advantageously, the end material 200may have a monolithic amorphous structure with low porosity. The endmaterial 200 may be stronger and lighter than concrete and brick, andresistant to moisture and chemicals. Exemplary end material 200 may bemade by curing non-toxic acrylic-based oligomers and a minimal quantityof photoinitiator, so the making of end material 200 may be safer forhealth.

Although FIG. 2 shows the end material 200 as including the firstadditive 204 and the second additive 206 for illustrative purposes only,the end material 200 may include no additives, or may include any numberof uniform and/or different additives, without limitation. Use of thesame matrix material 202 with various combinations of the additives inthe end material 200 allows obtaining the end material 200 for a widerange of applications.

FIG. 3 illustrates an embodiment of a system 300 for generating thephotopolymer composite resin for use in a 3D printing system. The system300 comprises a drum 302, a barrel pump 304, a flow meter 328, a ribbonblender 306, a discharge valve 308, a pump 310, and a mixing tank 316 ofa 3D printing system 332.

A drum 302 comprising the acrylate oligomer 320 may be moved to thelocation of the barrel pump 304. The lid of the drum 302 is cleaned toremove any dust. A special tool to remove the barrel cap (the larger ofthe two on the drum's lid) is utilized and placed on the lid of thedrum. The level of acrylate oligomer 320 inside the drum is measured andshould be between about 1-3″ from the top. A barrel pump 304 isinstalled into the cap hole of the barrel in a vertical position. Thebarrel pump 304 is placed in fluid communication with a ribbon blender306 that has been emptied and has the discharge valve 308 in the“closed” position. The barrel pump 304 is activated and the flow rate ofthe acrylate oligomer 320 into the ribbon blender 306 is monitoredthrough a flow meter 328. The barrel pump 304 is turned off soon as therequired volume of the acrylate oligomer 320 is reached inside theribbon blender 306. If the drum 302 is emptied during the pumpingprocedure, the barrel pump 304 is turned off and is reinstalled onto thenext drum to continue pumping.

After the acrylate oligomer is added to the ribbon blender 306, thepowdered components 318 may be added into the ribbon blender. Thepowdered components 318 may comprise the UV initiator 326, the inorganichydrate 322, and the reinforcing filler 324.

The UV initiator 326 may be added to the acrylate oligomer 320 withinthe ribbon blender 306 ranging between about 0.001 to 0.2 w % of theformulation. The UV initiator 326 is loaded into the ribbon blender 306.The empty container of the UV initiator is weighed to ensure that thedesired amount of UV initiator 326 was added to the ribbon blender 306.If some amount of UV initiator was not loaded into the ribbon blender306, the loading procedure should be repeated. After the UV initiator326 has been added, the container is closed to protect the powder fromsunlight and moisture.

The reinforcing filler 324 may be added after the UV initiator 326. Insome instances, the reinforcing filler 324 comes in 551 b bags. Toensure that the correct amount of the reinforcing filler 324 is added,the bag of the reinforcing filler 324 is placed on a floor scale andweighted to obtain the total mass of the load. A safety grating isinstalled within the ribbon blender 306, and the bag of the reinforcingfiller 324 is opened and loaded into the ribbon blender 306 through thesafety grating. When the bag is emptied after loading, the empty bag isweighed. A calculation is performed to calculate the mass of reinforcingfiller inside the ribbon blender 306 by subtracting the weight of theemptied bag from the total mass weight taken initially. Additionalquantities of the reinforcing filler are added to the ribbon blender 306to meet the quantity range of about 5.0 to 60.0 w % of the formulation.The ribbon blender 306 is then turned on for about 10 minutes to form apremix resin from the components before adding the inorganic hydrate.

The inorganic hydrate 322 may be added after the reinforcing filler 324.In some instances, the inorganic hydrate 322 comes in 551 b bags. Toensure that correct amount of the inorganic hydrate 322 is added, thebag of the inorganic hydrate 322 is placed on a floor scale and weightedto obtain the total mass of the load. A safety grating is installedwithin the ribbon blender 306, and the bag of the inorganic hydrate 322is opened and loaded into the ribbon blender 306 through the safetygrating. When the bag is emptied after loading, the empty bag isweighed. A calculation is performed to calculate the mass of inorganichydrate inside the ribbon blender 306 by subtracting the weight of theemptied bag from the total mass weight taken initially. Additionalquantities of the inorganic hydrate are added to the ribbon blender 306to meet the quantity range of about 20.0 to 70.0 w % of the formulation.Once the desired quantity has been loaded into the ribbon blender 306,the ribbon blender 306 is powered on to run for 12 hours in order to mixthe components.

The ribbon blender 306 is turned off and allowed to stop after runningfor about 12 continuous hours. The pump 310 is then positionedunderneath a discharge valve 308 of the ribbon blender 306. In anembodiment, the pump 310 is then connected to the mixing tank 316 of alarge gantry 3D printing system 332 through the use of a hose 330. Anyappropriate 3D printing system may be used, and the disclosure is notlimited to the large gantry 3D system. The gantry system (GS) mixingtank 316 is inspected to ensure that it is operational and that ready toreceive the mixed components as a resin. The pump is turned on beforethe discharge valve 308 is moved into the “open” position. The GS mixingtank is then inspected to ensure that the photopolymer composite resinis being collected. As soon as the flow rate of the resin pouring fromthe ribbon blender 306 starts to decrease, the ribbon blender 306 isturned on to push the remnants of the resin into the pump's hopper. Thepumping procedure ends when the ribbon blender 306 is emptied, at whichpoint the blender and the pump are turned off.

In some instances, the GS mixing tank 316 may be unavailable to receivethe photopolymer composite resin, and the resin may be loaded into astorage drum 312. The hose connected to the pump is positioned andsecured within the storage drum 312 instead of the GS mixing tank. Thepump is turned on before the discharge valve 308 is moved into the“open” position. As soon as the flow rate of the resin pouring from theribbon blender 306 starts to decrease, the ribbon blender 306 is turnedon to push the remnants of the resin into the pump's hopper. Thephotopolymer composite resin from the ribbon blender 306 may be pumpedinto at least one storage drum 312 due to total volume of the resinwithin the blender. If a pump cannot be used, an empty drum is placedunderneath the discharge valve 308 and the discharge valve 308 is openedto pour the photopolymer composite resin into the drum. The dischargevalve 308 is then closed as soon as the drum is full.

Before printing with the photopolymer composite resin stored in astorage drum 312, the resin requires some mixing. A mixer 314 such as amanual mixer may be utilized to mix the resin before transferring theresin to a GS mixing tank. The lid of the storage drum 312 may be openedand the paddle of the mixer may be positioned into the drum between thecenter of the drum and the inner wall. The upper layer of the resin maybe mixed by moving the paddle clockwise while it is on. The upper layerof the resin is mixed until the upper layer of the drum becomeshomogenous. The paddle may then be pushed to the bottom of the drum. Thebottom layer may then be mixed by moving the paddle outward from thecenter. The paddle may then be lifted towards the upper layer of theresin near the inner wall of drum and pushed back down towards thebottom of the drum while being moved in a counterclockwise rotationaround the center of the drum. The mixing continues until the resin ishomogenous.

To prevent the contamination of the inner surface of the blender withthe dye, which will influence the production of uncolored resin, thecoloring procedure may be carried in one of the storage drums, which maythen be labeled in accordance with the color of the dye used.

The necessary amount of dye is weighed out and placed into a layer ofresin within the drum. A manual mixer may be utilized to mix the dyewith the photopolymer composite resin. After the dye has been added, theresin in the drum may be mixed again after about 24 hours of storagebefore it is ready to be transferred to the GS mixing tank for use in 3Dprinting.

After about 12 hours of continuous mixing, the photopolymer compositeresin may be considered to be ready for use. The photopolymer compositeresin may require handling while in storage. In cases when the resin ispumped into the GS mixing tank, it may be mixed continuously until it isall consumed. Up to about 3 hours without mixing is acceptable. In caseswhere the resin is kept in drums for long-term storage, the followingrequirements must be met:

Drums must be sealed at all times

Avoid exposing the resin to light and moisture

No foreign impurities are allowed in the drum

Once every 7 days, the resin may be manually mixed

No printing with the resin is possible after about 3 hours of stayingunmixed

In some instances, the resin undergoes a quality assurance process.After the resin has been mixed for about 12 continuous hours, a 500 mLbatch is taken for testing. Three samples are to be obtained whilepumping the batch out from the ribbon blender. All samples are to betaken from the hose end to the GS mixing tank or in the second drum.

The first sample may be taken in the amount of about 150 to 200 mL at 10to 15 seconds after the start of the pumping procedure. The secondsample may be taken in the amount of about 150 to 200 mL in the middleof the pumping procedure. The third sample may be taken in the amount ofabout 150 to 200 mL at 10 to 15 seconds before the end of the pumpingprocedure.

In case of drum storage, the sampling procedure is as follows:

A first sample of about 150 to 200 mL may be taken from the first drum

A second sample of about 150 to 200 mL may be taken from the second drum

A third sample of about 150 to 200 mL may be taken from the third drum

The storage produced utilized three different drums since a single loadof the mixer may be equal to three drums volume. About 100 mL from eachsample may be put into a glass or PE container, mixed well, and sealedfor the QA procedures.

FIG. 4 illustrates an example embodiment of an industrial system 400 forproducing the photopolymer-based composite material formulation. Thesystem 400 is an example of a configuration for handling large volumesof the initial compounds utilized in the production of the formulation.In the system 400, an oscillating sleeve 406 feeds the initiatoroligomer mixture 446 into a hopper 412 at a controlled speed. Anagitator 420 within the hopper 412 is utilized to feed the initiatoroligomer mixture 446 into a dosing machine 422 comprising a feeder, aweight hopper, and a valve, that feeds the initiator oligomer mixture446 into a drum 402 comprising the acrylate oligomer 410. A mixer 428 isplaced into the drum 402 and mixes the acrylate oligomer 410 and theinitiator oligomer mixture 446. After the initiator oligomer mixture 446and the acrylate oligomer 410 have been mixed, a drum pump 430 transfersthe mixture (initiator oligomer mixture 446) from the drum 402 into ahopper 434. The hopper 434 includes an agitator 432 that keeps theinitiator oligomer mixture 446 from separating. Concurrently, anoscillating sleeve 404 is utilized to load the reinforcing filler 438into a hopper 436, and an oscillating sleeve 408 is utilized to load theinorganic hydrate 440 into a hopper 452.

Following the loading of hopper 434, hopper 436, and hopper 452, a pump448 transports the initiator oligomer mixture 446 from the hopper 434 toa plurality of ribbon blenders 414, with the flow of the initiatoroligomer mixture 446 being monitored by a flow meter 450. A dosingmachine 426 transfers the reinforcing filler 438 from the hopper 436 tothe plurality of ribbon blenders 414, and a dosing machine 424 transfersthe inorganic hydrate 440 from the hopper 452 to the plurality of ribbonblenders 414. The plurality of ribbon blenders 414 blends the initiatoroligomer mixture 446 with the inorganic hydrate 440 and the reinforcingfiller 438 for a period of time until the formulation 442 is releasedthrough a valve 444 into a feeder 418 that loads the formulation 442into at least one GS mixing tank 416.

Referencing FIG. 5, a method 500 of generating a formulation of aphotopolymer composite material for use in a 3D printing system involvescombining an acrylate oligomer ranging between about 20.0 to 60.0 w % ofthe formulation, an ultraviolet (UV) initiator ranging between about0.001 to 0.5 w % of the formulation, and a reinforcing filler rangingbetween about 5.0 to 60.0 w % of the formulation, in a blender (block502). In block 504, the method 500 generates a resin premix by blendingthe acrylate oligomer, the UV initiator, and the reinforcing fillerthrough operation of the blender for a first amount of time rangingbetween about 5 and 20 minutes±0.5 minutes. In block 506, the method 500combines the resin premix with an inorganic hydrate ranging betweenabout 20.0 to 70.0 w % of the formulation in the blender. In block 508,the method 500 generates a photopolymer composite resin by blending theinorganic hydrate and the resin premix through operation of the blenderfor a second amount of time ranging between about 10 and 14 hours±0.1hours.

In some configurations, the method 500 loads the photopolymer compositeresin from the blender into a mixing tank of a 3D printing system (block510).

In some instances, the mixing tank is not available and the method 500loads the photopolymer composite resin from the blender into a seconddrum for storage (block 512). The photopolymer composite resin stored inthe second drum may be mixed with a mixer after a time interval rangingbetween about 3 hours to 7 days±0.2 hours before it is transferred fromthe second drum into a mixing tank of a 3D printing system.

FIG. 6 illustrates an embodiment of a system 600 for generating thephotopolymer composite resin for use in a 3D printing system. The system600 comprises a drum 602, a barrel pump 604, a flow meter 606, a ribbonblender 608, a discharge valve 610, a pump 612, a hose 614, and a mixingtank 616 of a 3D printing system 618.

A drum 602 comprising the organic matrix 624 may be moved to thelocation of the barrel pump 604. The organic matrix 624 may comprise atleast one of an acrylate monomer and an acrylate oligomer. The lid ofthe drum 602 may be cleaned to remove any dust. A special tool may beplaced on the lid of the drum to remove the barrel cap (the larger ofthe two on the drum's lid). The level of organic matrix 624 inside thedrum may be measured and at between about 1-3″ from the top. A barrelpump 604 may be installed into the cap hole of the barrel in a verticalposition. The barrel pump 604 may be placed in fluid communication withan empty ribbon blender 608. The blender's discharge valve 610 may be inthe “closed” position. The barrel pump 604 may be activated, and theflow rate of the organic matrix 624 into the ribbon blender 608 may bemonitored through a flow meter 606. The barrel pump 604 may be turnedoff as soon as the required volume of the organic matrix 624 has beentransferred to the ribbon blender 608, such that the organic matrix 624may be found ranging between about 10.0 to 30.0 w % of the formulation.If the drum 602 is emptied during the pumping procedure, the barrel pump604 may be turned off and reinstalled onto the next drum to continuepumping.

After the organic matrix 624 is added to the ribbon blender 608, thepowdered components 626 may be added into the ribbon blender. Thepowdered components 626 may comprise the UV initiator 632, the inorganichydrate 628, and the reinforcing filler 630.

The UV initiator 632 may be added to the organic matrix 624 within theribbon blender 608 ranging between about 0.001 to 0.2 w % of theformulation. The empty container of the UV initiator 632 may be weighedto ensure that the desired amount of UV initiator 632 has been added tothe ribbon blender 608. If some amount of UV initiator 632 has not beenloaded into the ribbon blender 608, the loading procedure may berepeated. After the UV initiator 632 has been added, the container maybe closed to protect the powder from sunlight and moisture.

The co-initiator 634 may be added to the organic matrix 624 within theribbon blender 608 ranging between about 0.001 to 0.05 w % of theformulation. The empty container of the co-initiator 634 may be weighedto ensure that the desired amount of co-initiator 634 has been added tothe ribbon blender 608. If some amount of co-initiator 634 has not beenloaded into the ribbon blender 608, the loading procedure may berepeated. In some configurations, the co-initiator may be added into aformulation in advance. In some configurations, the co-initiator may bedissolved in a suitable organic solvent 636 separately from thecomposition mixture and may be added into a formulation right beforeextrusion by the 3D printing system 618.

In some formulations, an acrylic prepolymer may be generated byshort-term irradiation of acrylic monomers/oligomers combined withlimited amount of photoinitiator. This action may increase viscosity ofthe acrylic monomers/oligomers to prevent filler particles fromsedimentation and may allow the reactivity of the resulting mixture tobe adjusted.

The reinforcing filler 630 may be added after the UV initiator 632. Insome instances, the reinforcing filler 630 may come in 551 b bags. Toensure that the correct amount of the reinforcing filler 630 is added,the bag of the reinforcing filler 630 may be placed on a floor scale andweighted to obtain the total mass of the load. A safety grating may beinstalled within the ribbon blender 608, and the bag of the reinforcingfiller 630 may be opened and loaded into the ribbon blender 608 throughthe safety grating. When the bag is emptied after loading, the empty bagmay be weighed. The mass of reinforcing filler 630 inside the ribbonblender 608 may be calculated by subtracting the weight of the emptiedbag from the total mass weight taken initially. Additional reinforcingfiller 630 may be added to the ribbon blender 608 to meet the quantityrange of about 50.0 to 80.0 w % of the formulation. The ribbon blender608 may then be turned on for about 10 minutes to form a premix resinfrom the components before adding the inorganic hydrate 628.

The inorganic hydrate 628 may be added after the reinforcing filler 630.In some instances, the inorganic hydrate 628 may come in 551 b bags. Toensure that the correct amount of the inorganic hydrate 628 is added,the bag of the inorganic hydrate 628 may be placed on a floor scale andweighted to obtain the total mass of the load. A safety grating may beinstalled within the ribbon blender 608, and the bag of the inorganichydrate 628 may be opened and loaded into the ribbon blender 608 throughthe safety grating. When the bag is emptied after loading, the empty bagmay be weighed. The mass of inorganic hydrate 628 inside the ribbonblender 608 may be calculated by subtracting the weight of the emptiedbag from the total mass weight taken initially. Additional inorganichydrate 628 may added to the ribbon blender 608 to meet the quantityrange of about 5.0 to 30.0 w % of the formulation. The ribbon blender608 may then be run for 12 hours in order to mix the components.

In some formulations, the resin premix may be generated by blending theorganic matrix 624, the UV initiator 632, the thermal co-initiator 634,and the fillers through operation of the ribbon blender 608 for a firstamount of time ranging between 5 minutes and 20 minutes, followed byblending with the thermal initiator 638 in liquid form for a secondamount of time ranging between 5 seconds and 60 seconds. The thermalinitiator 638 may be at least partially dissolved in acrylate monomer toform the liquid thermal initiator.

In some formulations, the resin premix may be generated by blending theorganic matrix 624, the UV initiator 632, the thermal co-initiator 634,and the fillers through operation of the ribbon blender 608 for a firstamount of time ranging between about 5 and 20 minutes, followed byblending with the thermal initiator 638 in powder form for a secondamount of time ranging between 30 seconds and 5 minutes. The thermalinitiator 638 may be added such that it may be found in the quantityrange of about 0.001 to 0.05 w % of the formulation.

The pump 612 may be positioned underneath a discharge valve 610 of theribbon blender 608. In an embodiment, the pump 612 may be connected tothe mixing tank 616 of a large gantry 3D printing system 618 through theuse of a hose 614. Any appropriate 3D printing system may be used, andthe disclosure is not limited to the large gantry 3D system. The gantrysystem (GS) mixing tank 616 may be inspected to ensure that it isoperational and ready to receive the mixed components as a resin. Thepump may be turned on before the discharge valve 610 is moved into the“open” position. The GS mixing tank 616 may be inspected to ensure thatthe photopolymer composite resin is being collected. When the flow rateof resin from the ribbon blender 608 starts to decrease, the ribbonblender 608 may be turned on to push the remnants of the resin into thepump's hopper. The pumping procedure may end when the ribbon blender 608is emptied, at which point the ribbon blender 608 and the pump may beturned off.

In some embodiments, the resin premix generated by blending the organicmatrix 624, the UV initiator 632, the thermal co-initiator 634, and thefillers through operation of the ribbon blender 608 for a first amountof time ranging between about 5 and 20 minutes may be blended with thethermal initiator 638 for a second amount of time directly in theextruder of the 3D printing system 618, before the resin premix isdeposited and cured.

In some instances, the GS mixing tank 616 may be unavailable to receivethe photopolymer composite resin, and the resin may be loaded into astorage drum 620. The hose 614 from the pump 612 may be positioned andsecured within the storage drum 620 instead of the GS mixing tank 616.The pump may be turned on before the discharge valve 610 is moved intothe “open” position. When the flow rate of resin from the ribbon blender608 starts to decrease, the ribbon blender 608 may be turned on to pushthe remnants of the resin into the pump's hopper. The photopolymercomposite resin from the ribbon blender 608 may be pumped into one ormore drums, based on the total volume of the resin within the ribbonblender 608. If a pump 612 cannot be used, an empty drum may be placedbeneath the discharge valve 610, and the discharge valve 610 may beopened to pour the photopolymer composite resin into the drum. Thedischarge valve 610 may be closed as soon as the drum is full.

In some embodiments, the resin premix generated by blending the organicmatrix 624, the UV initiator 632, the thermal co-initiator 634, and thefillers through operation of the blender for a first amount of timeranging between about 5 and 20 minutes may be stored for a period oftime up to 12 months before being blended with the thermal initiator 638for a second amount of time.

Before printing with the photopolymer composite resin stored in astorage drum 620, the resin may require mixing. A mixer 622 such as amanual mixer may be utilized to mix the resin before transferring theresin to a GS mixing tank 616. The lid of the storage drum 620 may beopened and the paddle of the mixer 622 may be positioned into the drumbetween the center of the drum and the inner wall. The upper layer ofthe resin may be mixed by moving the paddle clockwise with the mixer onuntil the upper layer of the drum becomes homogenous. The paddle maythen be pushed to the bottom of the drum. The bottom layer may then bemixed by moving the paddle outward from the center, then up toward theupper layer of the resin near the inner wall of drum, then pushed backdown toward the bottom of the drum while being moved in a counterclockwise rotation around the center of the drum. Mixing may continueuntil the resin is homogenous.

To prevent the contamination of the inner surface of the ribbon blender608 with dye/pigment 640, which may influence the production ofuncolored resin, the coloring procedure may be carried out onphotopolymer composite resin in storage drums, which may then be labeledin accordance with the color of the dye/pigment 640 used. The necessaryamount of dye/pigment 640 may be weighed out and placed into a layer ofresin within the drum. A manual mixer may be utilized to mix thedye/pigment 640 with the photopolymer composite resin. After thedye/pigment 640 has been added, the resin in the drum may be mixed againafter about 24 hours of storage before it is ready to be transferred tothe GS mixing tank for use in 3D printing.

After about 12 hours of continuous mixing, the photopolymer compositeresin may be considered to be ready for use. The photopolymer compositeresin may require handling while in storage. As resin is pumped into theGS mixing tank, it may be mixed continuously until it is all consumed.Up to about 3 hours without mixing may be acceptable. In cases where theresin is kept in drums for long-term storage, the following criteria mayneed to be met:

Keep drums sealed at all times

Avoid exposing resin to light and moisture

Keep foreign impurities out of drums

Manually mix resin once every seven days

Do not attempt to print with resin that has gone unmixed for more thanthree hours

In some instances, the resin may undergo a quality assurance process.After the resin has been mixed for about 12 continuous hours, a 500 mLbatch may be taken for testing. Three samples may be obtained whilepumping a batch out from the ribbon blender. All samples may be takenfrom the hose end to the GS mixing tank or the second drum.

A first sample of about 150 to 200 mL may be taken 10 to 15 secondsafter pumping begins. A second sample of about 150 to 200 mL may betaken in the middle of the pumping procedure. A third sample of about150 to 200 mL may be taken 10 to 15 seconds before pumping stops.

For resin in drum storage, the sampling procedure may be as follows:

A first sample of about 150 to 200 mL may be taken from the first drum

A second sample of about 150 to 200 mL may be taken from the second drum

A third sample of about 150 to 200 mL may be taken from the third drum

Storage in this embodiment may use three different drums, since a singleload of the mixer may be equal to three drums in volume. About 100 mLfrom each sample may be put into a glass or PE container, mixed well,and sealed for quality assurance procedures.

Referencing FIG. 7, a method 700 of generating a formulation of aphotopolymer composite material for use in a 3D printing system involvescombining at least one of an acrylate monomer and acrylate oligomerranging between about 10.0 to 30.0 w % of the formulation in a blender,along with an ultraviolet (UV) initiator ranging between about 0.001 to0.2 w % of the formulation, a co-initiator ranging between about 0.001to 0.05 w % of the formulation, a reinforcing filler ranging betweenabout 50.0 to 80.0 w % of the formulation, and an inorganic hydrateranging between about 5.0 to 30.0 w % of the formulation (block 702). Inblock 704, the method 700 generates a resin premix by blending theacrylate monomer/acrylate oligomer, the UV initiator, the co-initiator,the reinforcing filler, and the inorganic hydrate through operation ofthe blender for a first amount of time ranging between about 5 and 20minutes±0.5 minutes.

In block 706, the method 700 combines the resin premix with a thermalinitiator ranging between about 0.001 to 0.05 w % of the formulation inthe blender. In block 708, the method 700 generates a photopolymercomposite resin by blending the thermal initiator and the resin premixthrough operation of the blender for a second amount of time rangingbetween about 5 seconds and 5 minutes.

In some configurations, the method 700 loads the photopolymer compositeresin from the blender into a mixing tank of a 3D printing system (block710). In some instances, in an operation after block 704 and beforeloading the thermal initiator, the mixing tank may not be available andthe method 700 loads the photopolymer composite resin from the blenderinto a second drum for storage (block 712). In this scenario, block 712returns to block 706 for the addition of the thermal initiator. In someembodiments, this method may be performed because the combination of theresin premix and the thermal initiator cannot be stored together forlonger than about 1 hour. In other embodiments, the photopolymercomposite resin without the thermal initiator, stored in the seconddrum, may be mixed with a mixer after a time interval ranging betweenabout 3 hours to 7 days±0.2 hours before it is transferred from thesecond drum into a mixing tank of a 3D printing system.

FIG. 8 illustrates cellular structure concepts 800 comprising astructural wall 802, hollowed out portions 804, and an in-fill pattern808, while the structural wall 806 comprises just the in-fill pattern808. A wall structure with a special infill pattern may be utilized toincrease material load bearing capacity without using additionalreinforcement. The structural layers are printed using a cellularstructure for better tensile strength and integrity. The 3D printingmethod allows the building of structural elements with differentgeometries which are much better able to sustain loads compared to manymaterials commonly used in construction today.

Using a structural photopolymer-based composite in a solid state(without reinforcement threads or cell structure), internal testingindicates that the material is stronger than B25 and other commonly usedconcretes. This allows the building of solid structures with muchgreater material efficiency and supporting a much wider range of designpossibilities than traditional methods (so called free-formarchitecture).

The use of a cellular structure may be able to reinforce the inherentstrength of the photopolymer composite. Using the dimensional structureof a slab (ceiling board), the moment of inertia around the bending axiswas raised by a factor of 10 compared to a solid section of the samearea. Thus, the deformation of the slab was reduced by the same 10×.

The polymer has both greater compressive strength and elasticity thaneither concrete or brickwork. This may allow for the construction ofbuildings that are lighter and less prone to collapse: more compressivestrength provides walls and floors with a high load-bearing capacity ata lower overall weight, while elasticity helps a structure to withstanddeformations caused by overloads or unexpected environmental impacts(such as earthquakes). The lightweight construction reduces the load onthe foundation, which reduces construction costs.

TABLE 12 Properties of 3D Printed Photopolymer Composite MaterialMechanical Properties Value Ultimate compressive strength 66 ± 3 MPaCompressive modulus of elasticity 5600 ± 200 MPa Relative compressivedeformation  3.8 ± 0.5% Ultimate tensile strength 7.6 ± 0.9 MPa Tensilemodulus of elasticity 4400 ± 400 MPa Relative tensile deformation 0.18 ±0.03% Ultimate flexural strength 15 ± 1 MPa Flexural modulus ofelasticity 9200 ± 250 MPa Relative flexural deformation 0.19 ± 0.01%Thermal properties Thermal conductivity 0.42 ± 0.03 W/m · K Thermalcapacity 1430 ± 225.0 J/kg · K Fire safety Flame spread index 0-25 Smokedevelopment index 275 Environmental impact Moisture test Pass Salt fogtest Pass Thermal cycling from −60° C. to 60° C. Pass Sun radiation testPass Fungal stability Pass

The printed photopolymer composite material is an object which consistsof many flat, horizontal layers, with layer height ranging from about 3to 10 mm. The total structure of printed objects has some anisotropy ofmechanical properties, due to the layer-by-layer deposition. Someproperties of the photopolymer composite material may be shown in Table12.

To achieve a fire protection rating (FSR) below 25, the followingadditives are included in the formulation: sodium tetraborate, boricacid, and aluminum oxide trihydrate. These are inorganic additives ofintumescent action (i.e., they swell when heated). When the photopolymercomposite material burns, it produces water vapor and a protective crustof refractory alumina. Simply speaking, the polymer isself-extinguishing. Layers of different thicknesses may allow theformulations to achieve the target properties of FSR<25 under the NFPA(National Fire Protection Association) 255 Standard and allow thematerial to exhibit noncombustible/self-extinguishing properties.

The photopolymer composite material underwent open-fire tests comparingthe performance of a wall with modern Structural Insulated Panels (SIPs)comprising gypsum board, oriented strand board (OSB), and insulationfoam.

The photopolymer composite material was tested with a width of 12 mmagainst gypsum board of the same width to confirm its superiorfire-resistant properties as a stand-alone material. After 20 and 60minute open-fire tests, board made from the photopolymer compositematerial received much less damage than the gypsum board. As a result,the wall panel with the photopolymer composite material demonstratedmuch better performance across a number of parameters. The designedfire-resistant properties greatly outperform those of gypsum-cartonboard, the most commonly used thermal barrier material in the UnitedStates.

Additionally, the formed resin may provide weather protection withoutcavities or seams (which are inevitable with any modular construction).This may be due to the unique printing method, as well as thehydrophobic nature of the material. Due to the nature of thephotopolymer composite, the system may be able to create waterproofwalls across the exterior of a structure. Apart from moisture, theexterior barrier of the structure may be also able to protect theinternal wall structure from wind, dust, and other external influences,such as UV light. Another important climatic characteristic is thermalresistance (the inverse of thermal conductivity), expressed as theR-value.

Table 13 shows an example embodiment of the formulation for thephotopolymer composite material for use in a 3D printing system.

TABLE 13 Example Formulation of Photopolymer Composite for 3D PrintingComponents Quantity Ranges Organic Matrix (TEGDMA) 23 to 27 w %Inorganic Hydrate (Borax Decahydrate) 22 to 25 w % Reinforcing Filler(Al(OH)₃) 52 to 55 w % UV Initiator (BAPO)   0.001 w %

Table 14 shows some mechanical properties of the 3D printed photopolymercomposite material.

TABLE 14 Properties of 3D Printed Photopolymer Composite MaterialMechanical Properties Value Ultimate compressive strength 66 ± 3 MPaCompressive modulus of elasticity 5600 ± 200 MPa Relative compressivedeformation 3.8 ± 0.5% Ultimate tensile strength 7.6 ± 0.9 MPa Tensilemodulus of elasticity 4400 ± 400 MPa Relative tensile deformation 0.18 ±0.03% Ultimate flexural strength 15 ± 1 MPa Flexural modulus ofelasticity 9200 ± 250 MPa Relative flexural deformation 0.19 ± 0.01%

Table 15 shows the components and quantity of Test Formulation #1. TestFormulation #1 differs from the formulation in Table 13 in that thereinforcing filler is quartz powder.

TABLE 15 Test Formulation #1 Components Quautity Ranges Organic Matrix(TEGDMA)   23 w % Inorganic Hydrate (Borax Decahydrate)   433 w %Reinforcing Filler (Quartz powder)   51 w % UV Initiator (BAPO) 0.001 w%

Table 16 shows some mechanical properties of Test Formulation #1.

TABLE 16 Properties of Test Formulation #1 Mechanical Properties ValueUltimate compressive strength 56 ± 8 MPa Compressive modulus ofelasticity 2500 ± 400 MPa Relative compressive deformation 3.0 ± 0.5%Ultimate tensile strength 8.0 ± 1.0 MPa Tensile modulus of elasticity260 ± 40 MPa Relative tensile deformation 3 ± 0.5% Ultimate flexuralstrength 18 ± 3 MPa Flexural modulus of elasticity 7400 ± 1200 MPaRelative flexural deformation 0.26 ± 0.06%

When the mechanical properties of Test Formulation #1 and the exampleformulation are compared, the example formulation has a higher ultimatecompressive strength, two-fold higher compressive modulus of elasticity,and a slightly higher compressive deformation. Compared to the exampleformulation, Test Formulation #1 has a higher ultimate tensile strengthand relative tensile deformation, but significantly lower value for thetensile modulus of elasticity. The Test Formulation #1 has a higherultimate flexural strength and a higher relative flexural deformation,but a lower flexural modulus of elasticity value compared to the exampleformulation.

Table 17 shows the components and quantities for Test Formulation #2.Test Formulation #2 differs from the example formulation in Table 13 bythe low amount of borax decahydrate and a higher amount of the quartzpowder as the reinforcing filler.

TABLE 17 Test Formulation #2 Components Quautity Ranges Organic Matrix(TEGDMA)   25 w % Inorganic Hydrate (Borax Decahydrate)   15 w %Reinforcing Filler (Quartz powder)   60 w % UV Initiator (BAPO) 0.001 w%

TABLE 18 Table 18 shows some mechanical properties of Test Formulation#2 Properties of Test Formulation #2 Mechanical Properties ValueUltimate compressive strength 70 ± 11 MPa Compressive modulus ofelasticity 2500 ± 400 MPa Relative compressive deformation 3..6 ± 0.7%Ultimate tensile strength 10.0 ± 2.0 MPa Tensile modulus of elasticity280 ± 40 MPa Relative tensile deformation 3.5 ± 0.7% Ultimate flexuralstrength 24 ± 5 MPa Flexural modulus of elasticity 9400 ± 1400 MPaRelative flexural deformation 0.3 ± 0.06 %

When the mechanical properties of Test Formulation #2 and the exampleformulations are compared, Test Formulation #2 has a higher ultimatecompressive strength value, but lower compressive modulus of elasticityvalue and relative compressive deformation values. Test Formulation #2also has a higher ultimate tensile strength value and relative tensiledeformation value, but 16-fold lower tensile modulus of elasticityvalue. Additionally, Test Formulation #2 has higher values for ultimateflexural strength, flexural modulus of elasticity, and relative flexuraldeformation.

Table 19 shows components and quantities for Test Formulation #3. TestFormulation #3 differs from the example formulation in Table 13 bycompletely omitting the reinforcing filler.

TABLE 19 Test Formulation #3 Components Quautity Ranges Organic Matrix(TEGDMA)   30 w % Inorganic Hydrate (Borax Decahydrate)   70 w % UVInitiator (BAPO) 0.001 w %

Table 20 shows some mechanical properties for Test Formulation #3.

TABLE 20 Properties of Test Formulation #3 Mechanical Properties ValueUltimate compressive strength 61 ± 9 MPa Compressive modulus ofelasticity 2300 ± 350 MPa Relative compressive deformation 4.4 ± 0.7%Ultimate tensile strength 5.0 ± 0.8 MPa Tensile modulus of elasticity1280 ± 200 MPa Relative tensile deformation 0.25 ± 0.05% Ultimateflexural strength 20 ± 5 MPa Flexural modulus of elasticity 4300 ± 650MPa Relative flexural deformation 0.2 ± 0.06%

When the mechanical properties of Test Formulation #3 and the exampleformulation are compared, Test Formulation #3 has lower ultimatecompressive strength values and 2.4-fold lower compressive modulus ofelasticity values, but a slightly higher relative compressivedeformation value. Test Formulation #3 also has 1.5-fold lower ultimatetensile strength values, and a 3.4 times lower tensile modulus ofelasticity value, but a slightly higher relative tensile deformationvalue. Additionally, Test Formulation #3 has a higher ultimate flexuralstrength value and lower flexural modulus of elasticity value. TestFormulation #3 and the example formulation appear to have the samerelative flexural deformation value.

Table 21 shows the components and quantity of Test formulation #4. Testformulation #4 differs from the formulation given in Table 13 in thatthe organic matrix is TMPTMA.

TABLE 21 Test Formulation #4 Components Quautity Ranges Organic Matrix(TMPTMA) 23 to 29 w % Inorganic Hydrate (Borax Decahydrate) 22 to 24 w %Reinforcing Filler (Al(OH)₃) 50 to 54 w % UV Initiator (BAPO) 0.07 to0.09 w %

Table 22 shows some mechanical properties of Test formulation #4.

TABLE 22 Properties of Test Formulation #4 Mechanical Properties ValueUltimate compressive strength 46 ± 7 MPa Compressive modulus ofelasticity 2600 ± 600 MPa Relative compressive deformation 2.0 ± 0.8%Ultimate tensile strength 5.0 ± 1.5 MPa Tensile modulus of elasticity1500 ± 700 MPa Relative tensile deformation 0.3 ± 0.05% Ultimateflexural strength 20 ± 2 MPa Flexural modulus of elasticity 8400 ± 1400MPa Relative flexural deformation 0.23 ± 0.06%

When the mechanical properties of test formulation #4 and the exampleformulation are compared, the example formulation has a highermechanical performance. Ultimate compressive strength of the exampleformulation up to 43% higher than that of test formulation #4,compressive modulus of elasticity 2-fold exceeds the value ofcompressive modulus of elasticity of the test formulation #4. Tensileproperties of the example formulation exceed the properties of the testformulation #4 in 1.5-fold in ultimate tensile strength and in 3-fold intensile modulus of elasticity. The Test formulation #4 has a higherultimate flexural strength and comparable flexural modulus of elasticitywith the example formulation. Test formulation #4 possesses lowerstiffness in comparison with the example formulation.

Table 23 shows the components and quantity of Test formulation #5. Testformulation #5 differs from the formulation given in Table 13 in thatthe organic matrix comprises a mixture of TEGDMA and TMPTMA.

TABLE 23 Test Formulation #5 Components Quautity Ranges Organic Matrix(TMPTMA) 15 to 18 w % Organic Matrix (TEGDMA) 10 to 12 w % InorganicHydrate (Borax Decahydrate) 22 to 24 w % Reinforcing Filler (Al(OH)₃) 50to 54 w % UV Initiator (BAPO) 0.07 to 0.09 w %

Table 24 shows some mechanical properties of Test formulation #5.

TABLE 24 Properties of Test Formulation #5 Mechanical Properties ValueUltimate compressive strength 57 ± 7 MPa Compressive modulus ofelasticity 3400 ± 800 MPa Relative compressive deformation 2.0 ± 0.8%Ultimate tensile strength 8.0 ± 1.0 MPa Tensile modulus of elasticity4500 ± 700 MPa Relative tensile deformation 0.1 ± 0.05% Ultimateflexural strength 19 ± 2 MPa Flexural modulus of elasticity 8300 ± 1400MPa Relative flexural deformation 0.23 ± 0.06%

When the mechanical properties of test formulation #5 and the exampleformulation are compared, the example formulation has a highermechanical performance. Ultimate compressive strength of the exampleformulation up to 16% higher than that of test formulation #5,compressive modulus of elasticity 1.6-fold exceeds the value ofcompressive modulus of elasticity of the test formulation #5. Tensileproperties of the example formulation commensurate with the propertiesof the test formulation #5. Addition of 10-12 w % of TEGDMA into thetest formulation #4 improves the mechanical performance of thecomposite.

Table 25 shows the components and quantity of Test formulation #6. Testformulation #6 differs from the formulation given in Table 13 in thatthe organic matrix is PEGDMA.

TABLE 25 Test Formulation #6 Components Quautity Ranges Organic Matrix(PEGDMA) 23 to 29 w % Inorganic Hydrate (Borax Decahydrate) 22 to 24 w %Reinforcing Filler (Al(OH)₃) 50 to 54 w % UV Initiator (BAPO) 0.07 to0.09 w %

Table 26 shows some mechanical properties of Test formulation #6.

TABLE 26 Properties of Test Formulation #6 Mechanical Properties ValueUltimate compressive strength 165 ± 25 MPa Compressive modulus ofelasticity 1000 ± 600 MPa Relative compressive deformation 32.0 ± 5.0%Ultimate tensile strength 25.0 ± 4.0 MPa Tensile modulus of elasticity43. ± 65MPa Relative tensile deformation 6.0 ± 0.6% Ultimate flexuralstrength 50 ± 10 MPa Flexural modulus of elasticity 2400 ± 400 MPaRelative flexural deformation 2.0 ± 0.6%

When the mechanical properties of test formulation #6 and the exampleformulation are compared, the test formulation #6 has 2.5-fold higherultimate compressive strength and ultimate tensile strength than that ofthe example formulation. Tensile modulus of elasticity of the exampleformulation exceeds the property of the test formulation #6 in4-10-fold. The test formulation #6 possesses the highest elasticproperties.

The total structure of 3D printed parts may have some anisotropy ofmechanical properties, because of layer-by-layer deposition. The effectof anisotropy may manifest itself in the percent difference in theproperties of the printed parts along and across the deposited layers.However, a dual-curing system of initiators may reduce overallanisotropy of the printed parts. A comparative example showing theresulting products from the composition with and without the thermalinitiator is shown in Table 27.

TABLE 27 Properties of 3D Printed Dual-Cured Composite in comparisonwith the Photopolymerized Composite Dual-cured PhotopolymerizedParameter along across along across Ultimate 71 ± 4  70 ± 7  58 ± 3  66± 5  compressive strength, MPa Yield 60 ± 4  52 ± 5  47 ± 7  52 ± 4 strength, MPa Compressive 8400 ± 800  5400 ± 400  4100 ± 780  4600 ±1300 modulus of elasticity, MPa Relative 2.0 ± 0.8 3.0 ± 1.0 4.3 ± 0.65.0 ± 1.0 compressive deformation, % Ultimate tensile 10.5 ± 0.7  7.0 ±1.6  10 ± 1.0 5.5 ± 1.2 strength, MPa Tensile 11000 ± 1870  9400 ± 17005700 ± 680  5900 ± 1700 modulus of elasticity, MPa Relative tensile  0.1± 00.2 0.08 ± 0.02  0.2 ± 0.02  0.1 ± 0.03 deformation, %

A Photopolymerized Composite may be generated by blending the acrylatemonomers, the UV initiator, and the fillers shown in Table 28 throughoperation of the blender for 20 minutes. Dual-Cure Composite may begenerated by blending the acrylate monomers, the UV initiator, thethermal co-initiator, and the fillers shown in Table 28 throughoperation of the blender for 20 minutes. The thermal initiator may beadded to the premix just before the composite is extruded.

TABLE 28 Components of Composites for 3D Printing System QuantityRanges: Quanfity Ranges Components Dual-Cure Photopolymerization OrganicMatrix 23 to 29 w % 23 to 29 w % Inorganic Hydrate 22 to 24 w % 22 to 24w % Functional Filler 50 to 54 w % 50 to 54 w % UV Initiator 0.07 to0.09 w % 0.07 to 0.09 w % Thermal Initiator 0.03 w % 0 w % Co-initiator0.02 w % 0 w % Dye/pigment   0 w % 0 w %

Extrusion-based 3D printer equipped with a UV LED light source may beused for printing. The LED may be selected with the peak wavelength at417 nm. The maximum light intensity of the UV LED light source on thetop of the deposited layer may be 42 to 43 W/cm² with a diameter of spotsize of about 20 mm. The nozzle passage speed of 40 mm/sec may beapplied with the feeding rate of the composite into the nozzle (internaldiameter of 10 mm) of 2×10³ to 2.5×10³ mm³/sec, which may lead to theformation of the layer with a width of 16 mm and height of 4 mm.Photopolymerized material may be printed by applying 100% of the UV LEDlight source intensity. In case of dual-cure polymerization process, 3to 6% of the maximum intensity of the light source may be used. Theapplied light irradiation may allow control of the initiation of thepolymerization reaction at the surface. The chosen concentration of BAPOand light intensity may limit the penetration depth and allow thereaction to accumulate near the top surface of the deposited layer,thereby supporting the formation of the solid shell and avoidingdeformation of the surface due to rapid solidification and volumeshrinkage. As a result, the solid shell may form with the thickness of0.5 to 1 mm, which may hold the shape of the layer.

Compared to the composite polymerized by applying the dual-curingsystem, the photopolymerized composite may exhibit lower mechanicalperformance. For the dual-cured composite, the difference of 33% may beobserved for the ultimate tensile strength. The ultimate compressivestrength values along and across the printed layers may be equal. Thedecrease in difference between the properties of the printed parts alongand across the deposited layers may be caused by a reduction inanisotropy due to improved layer adhesion for the 3D printed parts. Thephotopolymerized composite may exhibit 14% distinction in the ultimatecompressive strength values and 45% distinction in the ultimate tensilestrength values. Higher stiffness of the dual-cured formulation may bedue to enhancement of the conversion degree of the material withinsequential photo- and thermal-polymerization curing.

The methods and formulations in this disclosure are described in thepreceding on the basis of several preferred embodiments. Differentaspects of different variants are considered to be described incombination with each other such that all combinations that upon readingby a skilled person in the field on the basis of this document may beregarded as being read within the concept of the invention. Thepreferred embodiments do not limit the extent of protection of thisdocument.

Having thus described embodiments of the present invention of thepresent application in detail and by reference to illustrativeembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of the presentinvention.

1. A method of generating a large-scale three-dimensional (3D) printedstructure, the method comprising: generating a resin premix by blendinga formulation of an acrylate monomer, acrylate oligomer, an ultraviolet(UV) initiator, an inorganic hydrate, a co-initiator, and a reinforcingfiller through operation of a mixing system for a first amount of time,the mixing system comprising a blender; combining a thermal initiatorwith the resin premix; and generating a photopolymer composite resin byblending the thermal initiator and the resin premix through operation ofthe blender for a second amount of time; extruding the photopolymercomposite resin via a 3D printing system; and applying a UV LED lightsource to the extruded photopolymer composite to initiate the hardeningof the photopolymer composite by activating the thermal reaction.
 2. Themethod of claim 1, wherein the an acrylate monomer and an acrylateoligomer are in the range between about 10.0-30.0 w % of theformulation, the UV initiator is in the range between about 0.001-0.2 w% of the formulation, the co-initiator in the range between about0.001-0.05 w of the formulation, the inorganic hydrate, comprising aborax decahydrate, is in the range between about 22.0-30.0 w % of theformulation, and the reinforcing filler, is in the range between about50.0-80.0 w % of the formulation, and the thermal initiator is in therange between about 0.001-0.05 w % of the formulation.
 3. The method ofclaim 1, further comprising: after generating the photopolymer compositeresin, loading the photopolymer composite resin from the blender into amixing tank of the 3D printing system.
 4. The method of claim 1, furthercomprising: combining with the resin premix a flame-retardant additivein the range between about 35.0 to 75.0 w % of the formulation, theflame-retardant additive including at least sodium tetraborate and boricacid.
 5. The method of claim 4, wherein the hardened photopolymercomposite is characterized as having a fire protection rating (FSR)<25.6. The method of claim 1, wherein the resin premix is characterized byhaving a first uncured state in the form of a thixotropic liquid with aUV light cure depth in the range of 5 mm to 15 mm.
 7. The method ofclaim 1, wherein the photopolymer composite resin is characterized ashaving a second cured state in the form of a hardened, non-liquidmaterial where the uncured composite resin has been exposed to a UVlight.
 8. The method of claim 1, further comprising: combining the resinpremix with a dye or pigment in the range between about 0.001-0.05 w ofthe formulation.
 9. The method of claim 1, wherein the thermal initiatoris at least partially dissolved in acrylate monomer to form a liquidthermal initiator, and the resin premix is combined with the liquidthermal initiator, and the second amount of time is in the range betweenabout 5 seconds to 60 seconds to achieve the proper mix of photopolymercomposite resin dependent on the printing speed and layer size.
 10. Themethod of claim 1, wherein the blender comprising a ribbon blenderhaving a discharge valve; and the mixing system comprises a first pumpin fluid communication with the ribbon blender, the pump configured topump the acrylate oligomer into the ribbon blender.
 11. The method ofclaim 1, further comprising: forming a structural wall with the hardenedphotopolymer composite, the structural wall having a plurality ofhollowed out portions.
 12. The method of claim 1, wherein the hardenedphotopolymer composite is characterized as having an ultimatecompressive strength of ranging from 66+/−3 Megapascal (MPa).
 13. Themethod of claim 1, wherein the hardened photopolymer composite ischaracterized as having a compressive modulus of elasticity of5600+/−200 Megapascal (MPa).
 14. The method of claim 1, wherein thehardened photopolymer composite is characterized as having an ultimatetensile strength of 7.6+/−0.9 Megapascal (MPa).
 15. The method of claim1, wherein the hardened photopolymer composite is characterized ashaving a tensile modulus of elasticity of 4400+/−400 Megapascal (MPa).16. The method of claim 1, wherein the UV LED light source has a maximumlight intensity of up to 43 W/cm2 with a diameter of spot size of about20 mm
 17. A method of generating a large-scale 3D printed structure, themethod comprising: generating a resin premix by blending a formulationof an acrylate monomer, acrylate oligomer, an ultraviolet (UV)initiator, an inorganic hydrate, a co-initiator, and a reinforcingfiller through operation of a mixing system for a first amount of timeranging between about 5 and 20 minutes, the mixing system comprising ablender; combining a thermal initiator with the resin premix; andgenerating a photopolymer composite resin by blending the thermalinitiator and the resin premix through operation of the blender for asecond amount of time ranging from about 10 and 14 hours before thephotopolymer composite resin can be considered ready for use; extrudingthe photopolymer composite resin via a 3D printing system, the 3Dprinting system comprising a nozzle and a UV LED light source; andapplying the UV LED light source at a first light intensity to theextruded photopolymer composite to harden the photopolymer composite.18. The method of claim 17, further comprising: applying the UV LEDlight source at a second light intensity to the extruded photopolymercomposite to further harden the photopolymer composite.
 19. The methodof claim 17, wherein the an acrylate monomer and an acrylate oligomerare in the range between about 10.0-30.0 w % of the formulation, the UVinitiator is in the range between about 0.001-0.2 w % of theformulation, the co-initiator in the range between about 0.001-0.05 w %of the formulation, the inorganic hydrate, comprising a boraxdecahydrate, is in the range between about 22.0-30.0 w % of theformulation, and the reinforcing filler, is in the range between about50.0-80.0 w % of the formulation, and the thermal initiator is in therange between about 0.001-0.05 w % of the formulation.
 20. The method ofclaim 17, wherein the thermal initiator is a powder and blending thethermal initiator in the range between about 30 seconds to 5 minutes tomix the thermal initiator into the resin premix based on the sprintingspeed and volume.
 21. The method of claim 17, further comprising:loading the photopolymer composite resin into a container for storage;and mixing the photopolymer composite resin at a time interval rangingfrom 3 hours to 7 days to maintain the ready to use state of thephotopolymer composite resin.